Abstract: Plant developmental processes are very flexible and highly depend on environmental factors. This is largely due to the existence of regulatory mechanisms that systemically control development on the whole plant level. In plants, regulatory peptides produced in the roots have been identified that are activated in response to different factors influencing root system, such as variation in the level of macronutrients (first of all, nitrogen and phosphorus) in the soil, influence of symbiotic microorganisms (soil rhizobial bacteria and arbuscular mycorrhiza fungi), and water deficiency. Among the systemically acting peptides, the most thoroughly investigated are CLE (CLAVATA3/EMBRYO SURROUNDING REGION-related) and CEP (C-TERMINALLY ENCODED PEPTIDES) peptides that are capable of travelling through the xylem from the roots to the shoot and triggering responses via binding to specific receptors operating in the phloem of the leaf. This review focuses on the role of these two groups of peptides in molecular dialog between the root and shoot.